Monday, November 26, 2007

Huge study on the population genetics of Native Americans

This is a pretty impressive study. They analyzed "678 autosomal microsatellite markers genotyped in 422 individuals" spread across the Americas. They also compare it to the CEPH panel of worldwide populationsInterestingly, or ironically, there are no samples from populations living in the United States. The authors claim that their study "represents the largest continent-wide Native American population-genetic study performed to date". I like the fact that they use the data to examine several of the main hypotheses regarding Native American population genetics. They include 2o figures and 30 or so tables in the supplementary material!! They don't seem to find anything too surprising...

Abstract: We examined genetic diversity and population structure in the American landmass using 678 autosomal microsatellite markers genotyped in 422 individuals representing 24 Native American populations sampled from North, Central, and South America. These data were analyzed jointly with similar data available in 54 other indigenous populations worldwide, including an additional five Native American groups. The Native American populations have lower genetic diversity and greater differentiation than populations from other continental regions. We observe gradients both of decreasing genetic diversity as a function of geographic distance from the Bering Strait and of decreasing genetic similarity to Siberians—signals of the southward dispersal of human populations from the northwestern tip of the Americas. We also observe evidence of: (1) a higher level of diversity and lower level of population structure in western South America compared to eastern South America, (2) a relative lack of differentiation between Mesoamerican and Andean populations, (3) a scenario in which coastal routes were easier for migrating peoples to traverse in comparison with inland routes, and (4) a partial agreement on a local scale between genetic similarity and the linguistic classification of populations. These findings offer new insights into the process of population dispersal and differentiation during the peopling of the Americas.